Abstract: Using the GPS TEC data from China Crustal Movement Observation Network and Jet Populsion Laboratry, this paper analyzes the M_S6.8 earthquake in the south of Sumatra island, Indonesia on August 2, 2019 by the sliding quartile method and studies the correlation between the Indonesia earthquake and the TEC anomaly in Sichuan and surrounding region. Through the monitoring of TEC in Sichuan and surronding region and the world, we can clearly found that on July 25, 2019 (one week before the earthquake), TEC anomaly occurred in the epicenter region of Indonesia earthquake and the magnetic conjugate region of the northern hemisphere. Combined with the statistical analysis from 2011 to 2019, it was found that most earthquakes of M_S6.0 and above in Indonesia induced TEC anomalies in the Sichuan and surronding region. In terms of time, the anomalies are concentrated in the 10 days before the earthquake to 4 days after the earthquake, and mainly occur from 6:00 to 11:00 (LT), where two peaks are formed at 7:00 and 10:00, with the less anomalies in the nights; spatially, the strong earthquakes in Indonesia with TEC anomaly in Sichuan area are concentrated in the west of Indonesia, which shows good correlation with TEC anomaly in Sichuan region, the TEC anomalies in the Sichuan region caused by strong Indonesian earthquakes is about 32×10⁴ km² , being huge and easy to monitor. In summary, The TEC anomalies in Sichuan and surrounding region has a significant spatial-temporal correlation with strong earthquakes in Indonesia. Combined with the global TEC anomaly mapping, TEC anomaly analysis in Sichuan region can play an important role for monitoring earthquakes in Indonesia.

Key words: TEC, Ionospheric anomalies, Indonesia earthquake, Sichuan and surrounding region